1. Technical Field
The present invention relates generally to a covering structure for buildings, and more particularly to a window blind which uses one single control module to collect or expand the covering material composed of slats or pieces of fabric.
2. Description of Related Art
By raising and lowering the covering material of a conventional window covering, the area to be shielded can be determined. The window coverings can be roughly divided into window blinds, cellular shades, roller shades, and sheer shades by the types or appearances of the covering materials. Among these classifications, a window blind generally has a covering material composed of a plurality of horizontally arranged shielding members, wherein the shielding members can be long slats or pieces of fabric which can be rolled up through a reel. The window blind using pieces of fabric as its covering material is also called a window roller blind.
Window coverings can be also divided into two types by either a cord is used or not. Each type has its own way of operation. The power of a cordless window covering can be provided by a spring or an electric source, wherein the covering material can be operated manually, or the state of the covering material can be changed through a human-machine interaction (HMI). On the other hand, window coverings having a cord can be further divided into two types: one uses a cord, and the other one uses a cord loop. A window covering using a cord has one single cord, and an end of the single cord is connected to the bottommost edge of the covering material, while another end thereof is exposed out after passing through the headrail of the window covering to be operated, so that the area shielded by the covering material can be adjusted by pulling the exposed cord. As for a window covering using a cord loop, a rotatable shaft tube or shaft is usually provided in the headrail, wherein the shaft tube or the shaft can be rotated as being driven by an exposed cord loop. By pulling the front or the rear sides of the cord loop, the covering material can be rolled up or expanded correspondingly.
However, no matter the covering material of a window blind is composed of a plurality of slats or pieces of fabric, and no matter how the covering material is operated, another adjusting mechanism is still required to adjust the inclination angle of each of the slats or to change the state (i.e., being rolled up or expanded) of each piece of fabric. In other words, a window covering has two separated mechanisms, one is for expanding or collecting the covering material, and the other one is for rolling up or expanding the pieces of fabric. Such design is inconvenient for operation.